The following
query, which I received last week, is longer than most queries I get,
but it articulates a common conundrum.

Q. My wife
is a service technician whose work involves crawling under houses, connecting
wires inside unsealed enclosures, wading through underbrush to access
phone line pedestals, and other activities that almost daily expose her
to encounters with bees, spiders, and snakes. While doing outdoor wiring
last week, she took the normal safety procedures of banging on the box
to make sure no wasp nest was inside and slowly opening it with a long
screwdriver in case there was a snake. No critters were detected, so she
began her work. As she reached in to disconnect some lines around the
connector block, she felt a severe burning sensation, much stronger than
a wasp sting, on the inside of her thumb.

That evening
her hand was swollen and what looked like a small water blister was at
the point where she was bit/stung. I could see no sign of a stinger or
body part, but saw three tiny spots that could have been punctures. The
next morning the bite area was extremely red, her entire forearm was reddish
almost to the elbow, and her hand was miserably uncomfortable. Her doctor
said it was a black widow bite and gave her antibiotics and steroids.
Could any other spiders or insects produce such a reaction? A friend,
also a medical doctor, told us it was more likely a brown recluse. We
know that spider and snake bites are uncommon but people like to attribute
their wounds and pain to something exciting and interesting rather than
the most likely culprits--ants, bees, or even thorns. From your experience,
does this sound like a black widow bite?

A. Confirming
what bit or stung your wife is probably not possible at this point, as
a variety of creatures can cause such symptoms and people's responses
to venom are extremely variable. Highly toxic species can deliver venom
in quantities so small that no reaction is evident. Or they can inject
higher levels that cause severe problems. Further variation in responses
is due to the physiology of the person. For example, a bee sting can be
an unpleasant but short-term event for one person whereas someone else
may experience a systemic reaction that can be fatal. Factors of age,
medical history, body weight, and even whether someone is taking antihistamines
at the time can make a difference in how a person reacts to a bite or
sting.

Thousands
of invertebrates (including virtually all spiders) are capable of injecting
venom, although some animals are too small to affect us. Anther option
for what bit your wife is a centipede, which could very well be in the
type areas where she puts her hands. I have been bitten twice by centipedes,
and the symptoms you describe are similar to my own experience, especially
the red dots and reddening of the arm. A wolf spider or other large spider
is also an option or, in some parts of the Southeast, a scorpion.
People can vary considerably in their responses to a brown recluse or
to a black widow bite. And many of the reports about how these spiders
affect us are probably flawed because in speculating about what caused
the bite or sting the attending physician or nurse indicted the wrong
species (which may have been neither one of them) with the ensuing symptoms.
All told, our reactions to the bites and stings of venomous animals are
so variable that sometimes neither biologists nor medical doctors will
be able to diagnose the cause when the animal itself is not seen.

As you say,
it might be "exciting and interesting" to hear an expert declare
that "the animal that bit (stung) you is the rare and potentially
dangerous three-eyed rock monster," but sometimes the experts are
just guessing. Very few, in fact let me change that to "none,"
have observed all of the physiological responses that can be expressed
by humans to the myriad invertebrates that defend themselves against us.